My Custom Block Isn't working

So this is the first time I'm using Concrete5.7, I used an older verison on other websites.

This is a fresh install in Concerete5.7.

I've tried creating my own Custom Block called CorporateEmployee (the folder in applications/blocks/ is called corporate_employee. The block installed correctly, but any time I try to drag the block onto an area it simply sits there idle, with the loading cursor icon going. It never actually adds the block to the area.